Method of and apparatus for sterilizing milk



June 2z, 1943. H. T. STIL-Es 2,322,721'

METHOD OF AND APPARATUS FOR STERILIZING MILK Filed Jan. 13; 19:59 2 sheets-sheet 1 frra/PA/fy 2 Sheets-Sheet 2 H. T. STILES METHOD OF AND APPARATUS FOR STERILIZING MILK Filed Jan.- 15, 1939 Jun 22, 1943.

Patented June 22, 1943 METHOD or AND APPARATUS For;

STERILIZING Y Herbert T. Stiles, SuffieliConn. Appleman' Januar-y 13, 1939, serial No. 12593116 1 5 Claims,

My invention relates to methods of and apparatus for sterilizing milk. 1

IIt has heretoforebeen proposed to sterilize milk` by pasteurizing the `same.1' However, the process of pasteurization is a slow one,` and requires considerable expensive equipment, it being necessary not only initially to coolthemilk, but thereafter to heat it to `a temperature of between 145 `and 155, and thereafter to--maintain it at that temperature -for a considerable time, Whereupon the milk has to be cooled again before it is bottled. As a result, approximately an hour is required to eiect pasteurization, and the equipment is so expensive as to make it impractical, even for farms milking as many as one -hundred cows, to provide such equipment. Accordingly, it has been the practice only for very -large dairy `farms to provide pasteurizing equipment. .Fur-

ther, the'cost of pasteurization is high, running from one half to one cent aquart. i

`My invention has among rits objects to vproduce an improved method of and apparatus for-sterib izing milk, whereby theselobjections to pasteurization are overcome. A further object of `my invention is to producesuch anl improved method and apparatus wherebyit ismade possi-ble yvery substantially to reduce the time required for sterilization, while also making it possible for this operation to be performed with sucha minimum of equipment as substantially-toextendthe *pos-` sible use of sterilizingapparatus ondairyfarms. Still further-objects of my invention are to make it possible to eliminatenot `only'all `necessity for initially cooling the milk, butalsoto eliminate any necessity forstorage, and further tomake i-t possible to sterilize the milk as it vcomes directly from the milking machine, and as i-t moves continuously from the latter tothe bottling machine. Still further objects of my invention are to lower the bacteria count and Vthejsterilizing` cost per quart very substantially as compared with pasteurizing. These and other objects of my improvements will, however, hereinafter more fully appear.

In the accompanying drawings, I have-shown for purposes of illustration one form of apparatus on which my improved method may be practiced.

In these drawings: Figure 1 is a diagrammatic` side elevation ,of

this apparatus, a portion of `the chlorinatingriar being broken away toracilitate illustratiom-and the wiring connections of the various `devicesrbeing diagrammatically shown;

Fig. 2 is a 4Vertical central sectional View through the chlorinatingjan-,the view being taken Vapproximately on line 1-2--42 ofFigureBi Fig. A3 is a transversexsection on r linea .3-..'3 ,of Figure .2; i .I i

,i Fig. VLis axdiagrammatic sectional; view of 1- the .morefully described.

electric sterilizer, the same being shown in Sec.- tiononline A?! `of Figure .1: y

Fig, 5 is .a partial vertical section Online 5,-5 ofFgurei; Fig. 6 is an enlarged vertical sectiongo-f the rotary ygas distributor mechanism, as Vwell as the milk `supply connections shown in Figure 2;

Fig. E? .is a detail sectional view of one of ,the milk jetsvorfnogzles;

Fig. .8 is a sectional view online 8.-8of Figure `6 .showing one of the gas fjets on the rotary distributor; y

Fig. 49 is adetailplan .view of the supports .for

.the milk .distributor connections `at the ,top of ,the

chlorinating jar; Fig. 10 is a side elevation shown in Figure 9, and

Fig. 1,1.is adetailsectional view on of Figure 3.

Referring more particularly to Athis .illustrative apparatus, itwill-be noted that the milk from the `of thev connections line l l-,H

.milking machines is delivered .directly to `a receiving 4tank I and .moves .continuously therefrom sto a vpressure/tank 2 and to andthrough a lchlorinating' mechanism, .generally `indicated .at

3, wherein .themilk ischlorinatedby what may be called a `flash system, Aquickly and,A effectively,

and I thereafter` continuously supplied to an electric :sterilizer andseparator, .generally indicated Aat 4, from whichlthe milkalsolpasses continuously -to bottling mechanism (notshown) through an `outlet 5; these vseveral mechanisms eachbeng improved and cooperating in an improved manner -to produce improved results,.as hereinafter `In-my improved construction,` the milkin the tankil is `preferably supplied to the tank` 2` under pressure-as, for example, Aby atsuitable Apump B,

herein an electrically operated pump .having a motor 1 connect-ibler-by conductorsrto the main power -1ine `L. vWhile the f `pressure, in .the -tank 2 Amay vary, a pressure of .35 to 40- pounds is pref 1 erablyprovided therein, iti .being` found that such av'pressure is adequate to maintain-the desired spraying action within the -chlorinating .mechanism "3. Thus, Aas' `rni'lk is Vsupplied from the milking machines, it is pumped continuously by the-pump 6 through a-pipe connection Bfbetween they-tanks .l and! A.and from thelatter'through a pipe t0 tothe chlorinating mechanism. 3.

This Ycl'i-lorrinati-ng Amechanism, as -shown A.in

structionadapted to make `anlimproved flash Achlorination possible. A s illustrated, itincl-udes -completely cleansed. lHerein,-this-`jar has an open bottom, a substantially/'cylindrical portion above the 1 latter, anda dome-like closed" top.

-jar'herein-also--hasanlanularl flange l2 on of a heating pad I5 having suitable heating eley ments I6 distributed over the same in such manner as to heat the jar II eiectively and quite uniformly over its entire area; these heating coils I6 herein being connected to the line L through usual conductors I'I. As a result of this construction, it will be evident that with the heating coils I6 suitably externally insulated, it-

is possible to heatthe jar II over its entire area, and accordingly producea quite high temperature within the latter. While this `temperature may vary, a temperature of: approximately 200 in the space toward the top of the jar is preferred.

Here also, it will be noted that a thermometer I8 is also preferablyconnected at thetop of the jar II andv extending Vinto .the latter, while` a suitable pressure gauge AI9 and a suitable pressure release valve for the escape of gas vunder conditions of improper operation, are similarly provided onrthe topof the jar communicating with the interior thereof.

Herein, improved milk spraying means are provided within the jar which spray therein the milk received from the pressure tankf2 through the pipe connection I, in such manner asthereby effectually to prepare the same forthoroughand quick chlorination as hereinafterdescribed. As shown, the connection I0 is suitablyremovably connected, as at 2|, to a pipe 22 extending in- `ward and havinga portion extending axially upward along the axis'of the jar and a funnel 23 underlying the jar I I, this funnel herein'likewise having a flange 24 on its top supported on the ring I3 between the latter and the jar flange I2. This pipe 22 is herein provided with a short upwardly extending portion 25 provided with an annular flange 26 at its upper end and removably connected, as'by a flange nut 2'I, to the lower end of a milk distributing head or member 28, herein supported on the body of a spider 29 having a seriesof, herein four, spaced arms 3D also connected at their periphery by an annular ange 3| disposed between the flanges I2'and 24 heretofore described. This member 23, as shown, is provided with a large axial milk receivingpassage 32 in its bottom'and withv communicating milk distributing passages 33 in a suitable number of milk spraying arms 34, herein four and disposed over the spider arms 3U. As shown, these spraying arms 34 extend upwardly and outwardly from the member` 23 at the bottom of the jar II to a point substantiallyzmidway between the top and thebottom thereof, where they are curved relative to the jar axis, asat 35, inv such manner as to conform generally tothe curvature of the inside surface of the top portion of the jar, the curvature of these arms 34 herein being such as to maintain the same equallyvspaced from the inside surface ofthe jar II throughout the remainder of the lengthv of these arms. Moreover, it will be observed that beginning at a point substantially above ther member 28, each of lthese arms is provided with suitable spaced,

outlets 36, herein carrying spray nozzles 3l suitv ablyvconnected over the same, all of these outlets and nozzlesherein being on vthe inside of the arms, in such manner thatall jets of ymilk are delivered inintersecting paths in,v intersecting planes and away Iromvthe inside surface lof the heating pad I5. As a result of this construction,

lSi:

it will be apparent that milk may be supplied under pressure through the pipe connections II and 22 and will be delivered in the form of sprays Vfrom the nozzles 3`Iwithin the curved portions 35 of the spray arms 34, all while maintaining the sprayed milk in an area spaced from the inner walls of the heated jar I I.

Here it will also be noted that the structure is such as to minimize accumulations of milk thereon and tomake it possible for all of the milk supply Yconnections to be readily cleansed.

VTo this end, the surfaces of the member 2 8 and arms 34 are so shaped and disposed as to expedite complete drainage. Further, the spider arms 30 are also both downwardly sloped toward the center of the jar and made of ridged cross section, as shown in Figure 1,1. Also, all connections are adapted to be separated to permit thorough cleansing, for example, the vmember 28 being removable upon removing the bracket 39 and nut 21, and the arms .34 forming a unit with this member 28 being readily cleansed when their end closures 38 are removed.

Operating upon the milk while it is in process of being sprayed inside the jarl II as above described, is alsoimproved means for delivering chlorine gas inside the jar in vsuch manner as to effect a ilash chlorination of the milk while the latter is in spray form. YThis means herein, as in a preferred construction, is also carried by the member 28, in such manner as also tovbe bodily removable therewith. It will Vbe noted, moreover, that it is disposed toward the bottom of the jar II and herein delivers below and away from the lowermost nozzles 3'I,V which it `will be noted herein deliver generally upwardly. Herein, this delivery means includes improved rotary means for distributing the gas in such manner as very effectively to sterilize the milk spray by contact, and so quickly as not to saturate the milk. Also, the gas is supplied from a suitable tank 4I through a pipe connection 42, the latter being removably connected, as at 43, to the funnel 23 and also connected through a suitable connection 44 to a vertically disposed passage 45 in an extension 4 6 extending upward axially of the member 28. Further, it will be observed that this member 46 has a swivel head 4I7on its upper end suitably connected thereto, as by a Iianged sleeve 48, and that this head has any suitable number of; herein two, gas distributing pipes or arms 49 extending downwardly and outwardly therefrom, herein in the same plane and on opposite sides of the'head 4I. Y As shown, each of these members is in the form of a tube threaded into the member 41 at its upper end and having 'a removable closure 50 onv its outer end, and is furthermore provided with a series of spaced and downwardly and inwardly directed apertures Y 5I. These apertures are also directed at a slight angle to the vertical plane including thearms 49 (Fig. 8), the apertures in one arm 49 being directed on one side of this plane while the apertures in the diametrically opposed arm lare Vdirected on the opposite side of the plane, as will beevident from Fig. 6. Thus, when gas .under the pressure maintained in the tank 4|, usually 100 pounds, is supplied through the pipe connections 42, 44 to the vertical supply connection 45 and from the latter to the distributing pipes 49,

`it will be apparent that the pressure of the gas it will be observed that the heat within the jar Il will act upon the gas escaping from the apertures 5I and cause the same to rise toward the top of the jar Il, through the milk spray and as the milk is flowing downward. Further, with the high temperature obtainable by reason of the heating pad, it will be evident that the gas will rise very rapidly. Also, as a result of the dispersion of the milk into spray form, and the pressure at which the milk is discharged downwardly, it will be evident that the actual time of contact between the downwardly moving milk and the upwardly moving gas will be very short, and such as to produce only a momentary or ilash contact. Nevertheless, all of the milk so sprayed will be brought into contact with the rising gas to a suicient extent to insure the destruction of bacteria, the desired uniformity in results being materially assisted by the distributing action of vthe rotating gas distributor and the distribution of the milk in spray form and in intersecting paths in spaced areas determined by the radially located spray arms provided. Attention here is moreover directed to the fact that the inside surface of the jar Il is so heated by the heating pad I5 as to tend to drive the gas away from the sides of the jar, and thereby cause the same to pass upward through the downwardly moving milk. Further, it will be evident that the effect of the temperal ture on the gas is not only such as to make the same pass upward rapidly through the milk, as described, but also such as to prevent the gas from settling o-n any milk in the funnel 23. Instead, the milk, after being subjected to a flash sterilization by the gas, will pass quickly wholly out of the Zone thereof and down through the openings between the arms 30 of the spider 29 into the funnel 23 from which it is continuously discharged. Attention here is also directed to the fact that when thus received into the funnel 23, the milk has a temperature of approximately 140 to 150, i. e. substantially below 160, the temperature at which the milk degenerates and begins to acquire a so-called cooked taste. Here note that, in order to provide a further suitable check on the operation of the apparatus, a suitable thermometer 52 is carried by the funnel 23.

Operating upon the milk as it ilows continu-- ously out of the bottom of this funnel 23, is also improved cooperating sterilizing and airv suction mechanism. As shown, the milk flows from the bottom of the funnel 23 through a pipe connection 53 which conveys it to the electric sterilizer 4. Herein, this sterilizer has electrodes 54 of generally common type, but the same herein are laterally spaced upright members disposed in parallel relation on the bottom of the milk chamber in` vsuch manner asl to require a horizontal flow therethrough. Moreover, it will be observed that the milk inlet connection 53 and the milk outlet connection 55 are disposed at diagonally opposite corners of the sterilizer` casing 56, in such manner that the milk must ilow slowly along and between the electrodes 54 in passing from one side passage 51 of that casing, communicating with the inlet 53, to the opposite and parallel side pas sage 58 thereof, communicating with the outlet 55, all in such manner as thereby to insure effective supplementary sterilization and maintain a temperature of approximately as ther milk flows through the electric sterilizer. Attention here is further directed to thel fact that this milk flow so distributes the milk that the same is spread over a quite considerable area, while being acted upon by the electric sterilizer, and in such manner as thereby to free or separate out any gas which'may be entrained therein. Moreover, attention is directed to the fact that improved means are provided for drawing away any remaining gas without reducing the temperature of the milk to any appreciable extent, a suction hood 59 being provided which encloses the top of the `sterilizer casing 56 and is provided with a suction connection- 60, herein connected to a suitable suction pump 6I driven by a motor B2 and connected by the usual conductors 53 to the line L. Thus, when the milk passes outof the electric sterilizer outlet 55, thersa'me is at a temperature and in such condition that it may be supplied through usual cooling mechanism to a usual bottling mechanism.

As a result of my improvements, it is found that the complete process of sterilizationl can be carried out in only a fraction of the time 4heretofore required in pasteurization. In fact, it is possible to complete the entire circuit of the milk from the milking machine into the bottles in approximately iive minutes.` Further, the milk when so treated, due to my improved flash process, is wholly free either from any suggestion of chlorine or'of a cooked. taste, while, the whole process being performed in a sealed circuit, the bacteria count is substantially lower than that obtained by pasteurization. At the same time that the cost of the equipment is substantially less than that required for pasteurization, it will also be evident that the operating cost of the necessary equipment is negligible, the operating cost per quart of milk amounting to only a'minute frac i tion of a cent, as compared with varying from a half aicent to a cent per quart for pasteurization. Moreover, the apparatus is such that once the routine is learned, the process is, capable of being carried out by the average dairy farmer who, through the new quite general use of chlorine for cleansing purposes, is already familiar with the use 'of the same. These and other advantages of my improvements will, however, be apparent to those skilled in the art.

While I have herein speciiically described my improved method in connection with one form of apparatus capable of use in carrying out the same, it will be evident that my improved method may be practiced in connection with other apparatus, and it will further be understood that both my improved method and apparatus have been described herein for illustrative purposes and may be modified without departing from the spirit of my invention or the scope of the appended claims.

` What I claim asnew `and desire to secure by Letters Patent 1. The 'step in lsteril'izin'g milk which consists in, flash sterilizing `milk spray with previously unheated chlorine gas while heating the gas to cause it to rise through the milk spray and maintaining the gas out of contact with the collecting bulk milk.

2. The method of sterilizing milk which consists in, ash sterilizing the milk in a heated chamber while the milk is in spray form by exposing the sprayed milk to previously unheated sterilizing chlorine gas heated and rising in said heated chamber, and collecting the sterilized milk in bulk form outside the sterilizing zone in said heated chamber. v

3, The methodofsterilizing milk which consists in, spraying themilk in a dome, discharging sterilizing chlorine gas into said dome into intimate contact-with the milkv spray, heating said dome to heat said gas to cause it to expand and rise while activating the same, and collecting the sterilized milk in bulk form in a lower temperature zone below said heated dome.V

4. `The method of sterilizing milk-which consists in, delivering milk in spray form toward the center of a sterilizing chamber, expanding sterilizing chlorine gas in said chamber below the sprayed milk, and heating the wallsvof said sterilizing chamber to heat said gasto cause it to move inwardly and upwardly through the descending milk spray.

5. The method of sterilizing milk which con sists in, flash sterilizing the milk while the latter is in spray form with rising sterilizing chlorine gas, collecting the sterilized milk in bulk form while maintaining the bulk milk out of contact with the gas, and liberating any sterilizing gas in the bulk milk.r

6. The method of sterilizin'g milk which consistsin, ash sterilizing the milk while the latter is in spray form with rising sterilizing ychlorine gas, collecting the sterilized milk in bulk form while maintaining the bulk milk out of contact with the gas, and liberating any sterilizing gas in the bulk milk by subjecting the bulk milk to a suction,

7. Milk sterilizing apparatus including a sterilizing chamber having an open bottom, milk spraying means. delivering into said chamber, means for delivering sterilizing gas into said chamber above the open bottom thereof,fmeans for heatingl said chamber 13o heat the gas and cause the same to rise in said chamber through f the falling milkk spray, Vand unheated milk collecting means below the open bottom of said heated chamber maintaining the sterilized bulk milk out of contact with the rising gas.

8. Milk sterilizing apparatus including a dome open atthe bottom and forming a sterilizing chamber above said open bottom, milk spraying mechanism in said dome delivering milk in spray form inwardly from the walls of said dome toward the center of said chamber, means for introducing a sterilizing gas into said chamber below said milk spraying mechanism, and means for heating the top and adjacent side walls lof said dome to heat said gas and cause said gas to rise through the milk sprayed in said dome.

9. Milk sterilizing apparatus including a dome open at `the bottomand forming a sterilizing chamber above said open bottom, milk spraying mechanism in said dome for directing milkin spray form inwardly into said chamber, sterilizing gas delivering mechanism delivering gas in said chamber below said spraying mechanism, means for heating the portion ofthe walls of said dome in the vicinity Vof and enclosing said ber, sterilizing gas delivering mechanism delivering gas adjacent the bottom of said dome and delivering below the milk spraying mechanism therein, and, means for heating the top and adjacent side walls of said dome to cause said gas to rise in said chamber into said milk spray, said spraying mechanism comprising a series of spray arms having spray outlets delivering away from the inside surface of said dome and said gas delivering means being disposed below said spray outlets on said arms.

ll. In a milk sterilizing machine, a dome open atthe bottom and forming a sterilizing chamber above said open bottom, an external heating pad enclosing the top and adjacent side walls of said dome and heating the same, milk spraying mechanism inside said dome, means for supplying sterilizing gas through the sprayed milk in the area heated by said heating pad, and an unheated bulk milk receptacle below the open bottom of said dome closing the latter and collecting the sprayed milk out of contact with said rising gas and said heated dome.

l2. Apparatus Ilor sterilizing milk including mechanism for flash sterilizing the same with chlorine gas, receiving means receiving the sterilized bulk milk therefrom, means for maintaininga continuous ilow of milk through said flash sterilizing mechanism and said receiving means, and suction means for removing any liberated gas from the bulk milky while flowing in said receiving means.

13. Apparatus for sterilizing milk including a receptacle for receiving milk from milking machines, mechanism for flash chlorinating the milk, now controlling means for directing the chlorinated milk over a large area including flow directing bailles in t'he path of the milk, means for continuously supplying the milk from said receptacle through said flash chlorinator and said flow controlling means, and suction means for removing anyV liberated gas from the bulk milk while ilowing inV said flow controlling means,

14. Apparatus for sterilizing milk including mechanism for ilash. sterilizing the milk with sterilizing chlorine gas, means for collecting the" sterilized milk in bulk form out of contact with the gas, flow directing baiile means receiving bulk milk from said collecting means, rand means for drawing off gas from said receiving means.

l5. In a milk sterilizing mechanism, milk spraying mechanism including upwardly directed radially located spraying arms delivering-inwardly and comprising a series of upwardly and inwardly directed curved arms approaching one another at the top, and Vsterilizing gas distributing mechanism projecting upward into the space'between said arms and having rotating gas distributing arms rotating in said space and delivering gas in the path of the falling milk spray.

'4 'HERBERT T. STILE'S. l 

